[LLVMdev] GSoC 2011: Fast JIT Code Generation for x86-64

Eric Christopher echristo at apple.com
Tue Apr 5 15:13:03 PDT 2011


On Apr 5, 2011, at 2:49 PM, Tilmann Scheller wrote:

> The idea would be to use the same approach to generate machine code from LLVM IR, e.g. having chunks of LLVM MC instructions for the individual LLVM IR instructions (ideally describing the mapping with TableGen), glueing them together doing no dynamic register allocation, no scheduling.

*nod* If we were going to do that, I'd be up for replacing the scheme in fast-isel with that. I just don't see how the general method is going to be any different. Either you have to cover every bit of the IR, or you don't and you punt to a scheme like the DAG which has to cover everything.

That said, the compilation itself could be way slow as you mentioned with the binary translation. I'd be really curious where the overhead is. I'd liked to get that down for sure.

-eric



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